This invention relates generally to a safety valve for use in a hydraulic line system which prevents flow of a working hydraulic fluid above a specific flow rate and more particularly to a safety valve which is located in the barrel of a chute lift cylinder of a ready mix concrete truck.
The delivery chute on the rear of ready mix concrete trucks is conventionally raised and lowered by means of a hydraulic cylinder. In normal operating use, the chute is often full of concrete and held in position by a hydraulic cylinder. The hydraulic hose connected to the hydraulic cylinder is subject to wear, damage, and deterioration by the nature of its application. Frequent inspections for cuts, abrasions, wear, acid wash damage, etc., are necessary to prevent hose failure during operation. Failure may occur if the hose is not regularly inspected. Failure also results from damage occurring on the job site. Workers tugging and pulling on a heavy, full concrete chute can cause pressure spikes in the hydraulic fluid flowing through the chute lift hydraulic hose. Workers can also use the hydraulic hose connection to the cylinder as a hand hold which causes further damage and wear to the hose and connection. Previously damaged hoses may break from the pressure spikes in the chute lift hydraulic hose. A broken hose results in a sudden pressure loss and the fluid flow is no longer controlled. The sudden loss of pressure results in hydraulic fluid rapidly flowing from the hydraulic cylinder, resulting in the chute crashing downward and potentially seriously injuring workers.
What is needed is a way to prevent the chute from crashing downward due to a sudden loss of hydraulic fluid pressure.